Conventionally, for instance in a financial institution, automatic seal-imprint verification is executed by a computer in order to judge if a customer's stamp is the same as the one registered beforehand. Whether the seal-imprint currently stamped (that is, the sample seal-imprint) corresponds to the registered one has been judged by so-called template matching. Namely, judgment is made by comparing all the pixels between the sample seal-imprint and the registered one, and the sample one is recognized to be corresponding to the registered one when the identification ratio exceeds a certain value.